Blood drop generation devices also known as lancet devices, generate blood samples for use in performing various blood tests. Such devices create a small puncture or incision in the skin of the fingertip, although the puncture or incision can be made in other areas of the body such as the foot, arm, or leg.
Many prior art lancet devices employ spring loaded cutting blades enclosed within a casing or housing. The housing of the device is placed against the skin and the blade is released by a triggering mechanism in the device. The potential energy stored within the spring causes the blade to exit the housing to create a uniform puncture or incision in the skin which can be controlled in terms of location, depth, and sterility. Since the blade is concealed within the housing, the patient is unable to view the blade prior to, during, or after the puncturing of the skin which reduces the patient's anxiety.
Many of these prior art lancet devices are marketed as "safety" lancet devices because they include means for retracting the blade back into the housing after the puncture or incision has been made which advantageously reduces the danger a disease being spread through contact with the used blade of the device. This is an important feature since deadly viruses such as AIDS and Hepatitis can spread from accidental punctures obtained from lancets used previously on an infected patient. However, some of these "safety" devices are not truly safe in that the blade can be pushed out or accessed after use.
Another feature common to many prior art lancet devices is the use of a plunging cutting motion. More specifically the cutting blades are adapted to be plunged through the skin in a motion which is perpendicular to the skin. This produces an incision which matches the size of the cutting blade. Such lancets are exemplified by U.S. Pat. No. 5,133,730 issued on Jul. 28, 1992 to Biro, entitled DISPOSABLE RETRACTABLE FINGER STICK DEVICE AND METHOD FOR MAKING THE SAME and assigned to International Technidyne Corporation the assignee herein. In the Biro patent, a sharp blade is provided on a spring biased pivot arm which moves the blade out through an orifice in the lancet housing and then retracts the blade back into the housing. Although the blade is positioned on a pivot arm, the blade is directed perpendicularly into the surface of the skin. The shape of the blade helps the blade enter the skin and make the needed incision.
Other lancet devices that create plunge cuts are exemplified in U.S. Pat. No. 3,760,809 to Cambell, Jr. entitled SURGICAL LANCET HAVING CASING and U.S. Pat. No. 5,395,388 to Schrage, entitled SINGLE UNIT LANCET DEVICE.
In order to lower the manufacturing costs of lancet devices, designs with only two or three separate parts have been developed. Such designs generally employ a cutting blade held by a complex molded structure that both advances and retracts the blade. Examples of this type of lancet device design are shown in U.S. Pat. No. 4,553,541, entitled AUTOMATIC RETRACTABLE LANCET ASSEMBLY, to Bums, and U.S. Pat. No. 5,212,879, entitled METHOD FOR MANUFACTURING A DISPOSABLE-RETRACTABLE FINGER STICK DEVICE to Biro et al., which is assigned to International Technidyne Corp., the assignee herein. Although such lancet devices have fewer parts than earlier designs, they still tend to be relatively expensive to produce due to the complex nature of the tooling which requires frequent cleaning and maintenance, and the close tolerance nature of the parts. Accordingly, a substantially high percentage of rejected parts and significant downtime are associated with these prior art designs. Hence the cost of such lancet devices remain relatively high.
In many prior art lancet devices, expensive metal springs are used. In some designs the springs form a portion of the cutting blade. In other designs, the cutting blade is driven by the spring. In both cases, the springs add significantly to the overall cost of the lancet as well to the complexity of assembling the lancet with the spring in its compressed, ready-to-use orientation.
Accordingly there is need for a disposable safety lancet that eliminates the metal spring and which is relatively inexpensive to manufacture. There is a further need for a disposable safety lancet that addresses the full time safety issue by providing a triggering mechanism that once activated to propel the blade out and then into the case, cannot be reactivated or otherwise manipulated to cause the blade to be extended out of the case.